How would you try to teach your children a lesson on drinking and drugs and at what age?

Would you ever use such programs as National Geographic or talk shows that show people who have ruined their lives with drugs and alcohol like Dr. Phil or Oprah, to try to teach young teens the consequences of those risky behaviors or do you think that glamorizes everything and encourages the children to act out. What type of things have you used to teach your child/teen life lessons and at what age did you start talking about drugs and drinking?